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Microwaves have many advantages over convective heating in terms of time, space and energy consumption but do give problems of localised heating within the product to be dried. To prevent this thermal runaway phenomenon, which leads to combustion of lignite during drying, two knowledge-based expert control system interfaces were developed for switching between a zero mode and two proportional integral derivative modes. Experimental results demonstate that fixed power levels result in thermal runaway but that the hybrid switching control strategy can be used to dry lignite safely and efficiently to the target moisture content of 7%., Microwaves have many advantages over convective heating in terms of time, space and energy consumption but do give problems of localised heating within the product to be dried. To prevent this thermal runaway phenomenon, which leads to combustion of lignite during drying, two knowledge-based expert control system interfaces were developed for switching between a zero mode and two proportional integral derivative modes. Experimental results demonstate that fixed power levels result in thermal runaway but that the hybrid switching control strategy can be used to dry lignite safely and efficiently to the target moisture content of 7%.